1. Field of the Invention
The present invention relates to a flush toilet apparatus that discharges waste to a drain pipe by wash water.
2. Description of the Related Art
Examples of known systems for supplying wash water to a bowl portion of a flush toilet apparatus include a system of using high water pressure in a water pipe to supply water (direct-pressure type) and a system of supplying water from a tank arranged at a high place (tank type).
Since the direct-pressure-type flush toilet apparatus directly supplies water in the water pipe to the bowl portion, continuous washing is possible. However, if the apparatus is installed in an environment with a low water pressure in the water pipe, the flow rate of the wash water is reduced, and there is a problem that the washing performance is reduced.
Since the tank-type flush toilet apparatus uses potential energy of water stored in the tank to supply the water to the bowl portion, a large amount of wash water can be supplied without being affected by the water pressure in the water pipe. However, continuous washing is difficult because water needs to be poured into the tank after washing, and there is a problem that the flush toilet apparatus is not suitable for a situation in which the apparatus is frequently used.
Other than the apparatuses, a flush toilet apparatus with a system of supplying wash water to a bowl portion by a jet pump is proposed in recent years. For example, a flush toilet apparatus described in Japanese Patent Laid-Open No. 2004-156382 includes a tank storing water, and a jet pump unit is submerged and arranged inside of the tank. The jet pump unit includes a throat pipe. One end of the throat pipe is connected to a channel toward the bowl portion, and an opening is formed at the other end. When water is injected from an injection nozzle toward the inside of the throat pipe through the opening, a jet pump action is induced, and a large amount of water flows inside of the throat pipe toward the bowl portion. Not only the water injected from the injection nozzle, but also the water stored in the tank is drawn in and flows inside of the throat pipe. Therefore, a large amount of water is supplied to the bowl portion.
In this way, the flush toilet apparatus with the system of supplying wash water by the jet pump is configured to supply a large amount of water to the bowl portion by the jet pump action. This can suppress the reduction in the washing performance when the apparatus is installed in an environment with a low water pressure in the water pipe. The total amount of wash water supplied to the bowl portion is substantially equal to a sum of the amount of water stored in the tank and the amount of water injected from the nozzle. Therefore, the amount of water that needs to be stored in the tank is smaller than in the conventional tank type, and the tank can be downsized. Although water needs to be poured into the tank after the completion of washing of the bowl portion, the time required to pour water is shorter than in the tank type. Therefore, continuous washing is possible even if the flush toilet apparatus is frequently used.
In the flush toilet apparatus with the system of supplying wash water by the jet pump, the force of water in the throat pipe may be reduced by a reduction in the efficiency of the jet pump action, and the flow rate of water supplied to the bowl portion may be reduced. As a result, waste may not be discharged from the bowl portion, or the surface of the bowl portion may not be sufficiently washed.
The efficiency of the jet pump action may be reduced by an enlargement of resistance faced by the water flow in the throat pipe as a result of generation of stagnation and vortexes in the water flow in the throat pipe or as a result of interference with the water flow by the inner surface of the throat pipe. Therefore, to efficiently induce the jet pump action (to efficiently draw the water in the tank into the throat pipe), the stagnation and vortexes as well as the interference by the inner surface of the throat pipe need to be suppressed, and the resistance faced by the water flow in the throat pipe needs to be suppressed.
The stagnation and vortexes in the water flow in the throat pipe are mainly generated when a high-speed water flow from the nozzle reaches a part where the channel is not linear in the throat pipe (part where the channel is curved), and the water flow detaches from the inner surface of the throat pipe. Particularly, since the vicinity of the inlet of the throat pipe is close to the injection port of the nozzle, the high-speed water flow is unevenly distributed to part of the areas of the channel cross section, and the detachment occurs easily. Therefore, the stagnation and vortexes are easily generated when the channel in the throat pipe is curved near the inlet.
Consequently, the shape of the throat pipe can be devised to suppress the generation of the stagnation and vortexes. Specifically, a straight pipe portion linearly extending in the injection direction of the injection nozzle can be formed from the inlet of the throat pipe to the downstream.
The distribution of the flow velocity in the channel cross section is gradually equalized while the water flows through the straight pipe portion. Therefore, there is almost no uneven distribution of the high-speed water flow in the channel cross section on the downstream of the straight pipe portion. As a result, the detachment is less likely to occur in the curved part on the downstream of the straight pipe portion, and the stagnation and vortexes are also less likely to occur.
In the curved part, the inner surface of the throat pipe interferes with the water flow by changing the travelling direction of the water flow (water flow collides). If the channel in the throat pipe is curved near the inlet (if the straight pipe portion is short), there is interference by the inner surface of the throat pipe while the high-speed water flow is unevenly distributed to part of the areas of the channel cross section. Therefore, a reverse flow as well as stagnation and vortexes easily occur inside of the throat pipe, and the jet pump action is inhibited. On the other hand, if a long straight pipe portion is formed on the upstream of the throat pipe as described above, the uneven distribution of the high-speed water flow is alleviated, and the influence of the interference by the inner surface of the throat pipe on the water flow is suppressed (particularly, toward the inlet).
In this way, the formation of a sufficiently long straight pipe portion on the upstream (toward the inlet) of the throat pipe is effective in suppressing the resistance faced by the water flow in the throat pipe to thereby suppress the reduction in the efficiency of the jet pump action.
To house the throat pipe provided with the long straight pipe portion in a small tank, the central axis of the straight pipe portion can be inclined in the tank as in the flush toilet apparatus described in Japanese Patent Laid-Open No. 2004-156382. However, such a configuration increases water remained in the tank below the tilted suction port, i.e., wasteful water that is not supplied to the bowl portion as wash water. In a configuration that a large amount of wasteful water remains in the small tank that can store a small amount of water, the generation time of the jet pump action is short, and the washing performance cannot be sufficiently exerted.
The present invention has been made in view of the problems, and an object of the present invention is to provide a flush toilet apparatus with a system of supplying wash water to a bowl portion by a jet pump, wherein although an upstream part of a throat pipe is inclined relative to a horizontal surface, an amount of wasteful water can be reduced, and generation time of a jet pump action can be sufficiently ensured.